I have a set of 901 Series IV speakers with a Series V equalizer.
A. Is there any difference between the series IV and series V EQ? It seems to work fine.
B. It's my understanding that the Bose EQ provides a +/- 18 db variance to the high and low ends. Is that when the slides are maxed in either direction? What is the net gain when the EQ is zeroed out in the middle of the slides?
C. What does the BASS button do on the Series V EQ? It do not notice any variation in the sound either way.
A. There are differences to the EQ curve between the series IV and series V equalizers because the drivers in those series 901 speakers are made from different materials. While it should still work and pass audio, we don't recommend mix and matching speakers and EQ's as damage can occur.
B. I believe that is correct, though I don't know the details of the EQ curve used.
C. The 'Bass' button on the front of the EQ should function something like a 'Bass Boost' button. If it's not working, it could be a faulty switch in the EQ.